The invention relates to a process for producing linear profiles made of an elastomer material.
Linear profiles made of an elastomer material are used by way of example as wiper rubber for windshield wipers in motor vehicles. The wiper rubbers are usually injection-molded or continuously extruded. For this, a previously mixed starting material, for example an unvulcanized natural or synthetic rubber, is molded and vulcanized. For economic reasons it is usual to produce double profiles. To produce individual wiper rubbers, the double profiles are separated along a cut edge after the vulcanization process and during optional subsequent post treatment, this edge generally being the subsequent wiping edge.
The production of a wiper blade encompassing a wiper rubber is disclosed by way of example in DE-A 10 2005 000 851. A coating is applied to the wiper rubber in order to increase wear resistance via a reduction in coefficient of friction. Examples of coatings used are films or granulated materials. The coating here can be applied prior to or after the vulcanization process.
A process for producing a wiper blade is also disclosed in DE-A 101 25 045. The wiper blade comprises a wiper rubber with a wiper-rubber lip. The wiper-rubber lip has been manufactured to some extent from polyethylene, in order to reduce the dry coefficient of friction. The polyethylene here can either have been applied in the form of a coating to the wiper-rubber lip or can be present within the volume of the wiper-rubber lip.
In the wiper rubbers known from the prior art, the coating enters into permanent adhesive bonding with the wiper rubber material.
A disadvantage of the processes known from the prior art for producing wiper rubbers is that the profile, which after the shaping process has not yet been completely vulcanized, is deformed permanently by gravity and flotation forces in the salt bath used for the vulcanization process. The wiper-rubber profiles produced currently have high wall thicknesses, in order to minimize deformation. However, the high wall thicknesses generate a disadvantageous restriction on the functional properties of the wiper rubber, for example in respect of flipover noise.